conditionally disabling libltdl subconfigure

[Brice Goglin]

Hello,

I am working at embedding libltdl inside our project (hwloc, an Open MPI
subprojet). Our plugins are not expected to be enabled in the most
common cases. So I am trying to see if the libltdl sub-configure could
be skipped entirely unless really needed (when plugins are enabled, and
libltdl is indeed built). I got the usual failure when I tried to put
LTDL_INIT inside a conditional block so I am looking for something else now.

Modifying the subdirs variable before AC_OUTPUT seems to work. But this
hack may not be safe enough. Is there a better way to do this?

Thanks
Brice